feat: auto-detect latest champions version from Riot API

When championsVersion is empty, fetch the latest version from
ddragon.leagueoflegends.com instead of requiring a hardcoded value.

data/config.go

@@ -1,3 +1,33 @@
 package main
 
-const championsVersion = "16.2.1"
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+)
+
+// Set this to pin a specific version. Leave empty to auto-detect latest.
+var championsVersion = ""
+
+func getChampionsVersion() (string, error) {
+	if championsVersion != "" {
+		return championsVersion, nil
+	}
+
+	resp, err := http.Get("https://ddragon.leagueoflegends.com/api/versions.json")
+	if err != nil {
+		return "", fmt.Errorf("failed to fetch versions: %w", err)
+	}
+	defer resp.Body.Close()
+
+	var versions []string
+	if err := json.NewDecoder(resp.Body).Decode(&versions); err != nil {
+		return "", fmt.Errorf("failed to decode versions: %w", err)
+	}
+
+	if len(versions) == 0 {
+		return "", fmt.Errorf("no versions found")
+	}
+
+	return versions[0], nil
+}

data/main.go

@@ -11,7 +11,13 @@ import (
 )
 
 func main() {
-	champions, err := parser.ParseChampions(championsVersion)
+	version, err := getChampionsVersion()
+	if err != nil {
+		log.Fatalf("Failed to get champions version: %v", err)
+	}
+	fmt.Printf("Using champions version: %s\n", version)
+
+	champions, err := parser.ParseChampions(version)
 	if err != nil {
 		log.Fatalf("Failed to parse champions: %v", err)
 	}